Import file-5.10.
[dragonfly.git] / contrib / file / src / ascmagic.c
1 /*
2  * Copyright (c) Ian F. Darwin 1986-1995.
3  * Software written by Ian F. Darwin and others;
4  * maintained 1995-present by Christos Zoulas and others.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice immediately at the beginning of the file, without modification,
11  *    this list of conditions, and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 /*
29  * ASCII magic -- try to detect text encoding.
30  *
31  * Extensively modified by Eric Fischer <enf@pobox.com> in July, 2000,
32  * to handle character codes other than ASCII on a unified basis.
33  */
34
35 #include "file.h"
36
37 #ifndef lint
38 FILE_RCSID("@(#)$File: ascmagic.c,v 1.84 2011/12/08 12:38:24 rrt Exp $")
39 #endif  /* lint */
40
41 #include "magic.h"
42 #include <string.h>
43 #include <memory.h>
44 #include <ctype.h>
45 #include <stdlib.h>
46 #ifdef HAVE_UNISTD_H
47 #include <unistd.h>
48 #endif
49
50 #define MAXLINELEN 300  /* longest sane line length */
51 #define ISSPC(x) ((x) == ' ' || (x) == '\t' || (x) == '\r' || (x) == '\n' \
52                   || (x) == 0x85 || (x) == '\f')
53
54 private unsigned char *encode_utf8(unsigned char *, size_t, unichar *, size_t);
55 private size_t trim_nuls(const unsigned char *, size_t);
56
57 /*
58  * Undo the NUL-termination kindly provided by process()
59  * but leave at least one byte to look at
60  */
61 private size_t
62 trim_nuls(const unsigned char *buf, size_t nbytes)
63 {
64         while (nbytes > 1 && buf[nbytes - 1] == '\0')
65                 nbytes--;
66
67         return nbytes;
68 }
69
70 protected int
71 file_ascmagic(struct magic_set *ms, const unsigned char *buf, size_t nbytes,
72         int text)
73 {
74         unichar *ubuf = NULL;
75         size_t ulen;
76         int rv = 1;
77
78         const char *code = NULL;
79         const char *code_mime = NULL;
80         const char *type = NULL;
81
82         if (ms->flags & MAGIC_APPLE)
83                 return 0;
84
85         nbytes = trim_nuls(buf, nbytes);
86
87         /* If file doesn't look like any sort of text, give up. */
88         if (file_encoding(ms, buf, nbytes, &ubuf, &ulen, &code, &code_mime,
89             &type) == 0)
90                 rv = 0;
91         else
92                 rv = file_ascmagic_with_encoding(ms, buf, nbytes, ubuf, ulen, code,
93                                                  type, text);
94
95         free(ubuf);
96
97         return rv;
98 }
99
100 protected int
101 file_ascmagic_with_encoding(struct magic_set *ms, const unsigned char *buf,
102     size_t nbytes, unichar *ubuf, size_t ulen, const char *code,
103     const char *type, int text)
104 {
105         unsigned char *utf8_buf = NULL, *utf8_end;
106         size_t mlen, i;
107         int rv = -1;
108         int mime = ms->flags & MAGIC_MIME;
109
110         const char *subtype = NULL;
111         const char *subtype_mime = NULL;
112
113         int has_escapes = 0;
114         int has_backspace = 0;
115         int seen_cr = 0;
116
117         int n_crlf = 0;
118         int n_lf = 0;
119         int n_cr = 0;
120         int n_nel = 0;
121         int executable = 0;
122
123         size_t last_line_end = (size_t)-1;
124         int has_long_lines = 0;
125
126         if (ms->flags & MAGIC_APPLE)
127                 return 0;
128
129         nbytes = trim_nuls(buf, nbytes);
130
131         /* If we have fewer than 2 bytes, give up. */
132         if (nbytes <= 1) {
133                 rv = 0;
134                 goto done;
135         }
136
137         if ((ms->flags & MAGIC_NO_CHECK_SOFT) == 0) {
138                 /* Convert ubuf to UTF-8 and try text soft magic */
139                 /* malloc size is a conservative overestimate; could be
140                    improved, or at least realloced after conversion. */
141                 mlen = ulen * 6;
142                 if ((utf8_buf = CAST(unsigned char *, malloc(mlen))) == NULL) {
143                         file_oomem(ms, mlen);
144                         goto done;
145                 }
146                 if ((utf8_end = encode_utf8(utf8_buf, mlen, ubuf, ulen))
147                     == NULL)
148                         goto done;
149                 if ((rv = file_softmagic(ms, utf8_buf,
150                     (size_t)(utf8_end - utf8_buf), TEXTTEST, text)) == 0)
151                         rv = -1;
152         }
153
154         /* Now try to discover other details about the file. */
155         for (i = 0; i < ulen; i++) {
156                 if (ubuf[i] == '\n') {
157                         if (seen_cr)
158                                 n_crlf++;
159                         else
160                                 n_lf++;
161                         last_line_end = i;
162                 } else if (seen_cr)
163                         n_cr++;
164
165                 seen_cr = (ubuf[i] == '\r');
166                 if (seen_cr)
167                         last_line_end = i;
168
169                 if (ubuf[i] == 0x85) { /* X3.64/ECMA-43 "next line" character */
170                         n_nel++;
171                         last_line_end = i;
172                 }
173
174                 /* If this line is _longer_ than MAXLINELEN, remember it. */
175                 if (i > last_line_end + MAXLINELEN)
176                         has_long_lines = 1;
177
178                 if (ubuf[i] == '\033')
179                         has_escapes = 1;
180                 if (ubuf[i] == '\b')
181                         has_backspace = 1;
182         }
183
184         /* Beware, if the data has been truncated, the final CR could have
185            been followed by a LF.  If we have HOWMANY bytes, it indicates
186            that the data might have been truncated, probably even before
187            this function was called. */
188         if (seen_cr && nbytes < HOWMANY)
189                 n_cr++;
190
191         if (strcmp(type, "binary") == 0) {
192                 rv = 0;
193                 goto done;
194         }
195         if (mime) {
196                 if (!file_printedlen(ms) && (mime & MAGIC_MIME_TYPE) != 0) {
197                         if (subtype_mime) {
198                                 if (file_printf(ms, "%s", subtype_mime) == -1)
199                                         goto done;
200                         } else {
201                                 if (file_printf(ms, "text/plain") == -1)
202                                         goto done;
203                         }
204                 }
205         } else {
206                 if (file_printedlen(ms)) {
207                         switch (file_replace(ms, " text$", ", ")) {
208                         case 0:
209                                 switch (file_replace(ms, " text executable$",
210                                     ", ")) {
211                                 case 0:
212                                         if (file_printf(ms, ", ") == -1)
213                                                 goto done;
214                                 case -1:
215                                         goto done;
216                                 default:
217                                         executable = 1;
218                                         break;
219                                 }
220                                 break;
221                         case -1:
222                                 goto done;
223                         default:
224                                 break;
225                         }
226                 }
227
228                 if (file_printf(ms, "%s", code) == -1)
229                         goto done;
230
231                 if (subtype) {
232                         if (file_printf(ms, " %s", subtype) == -1)
233                                 goto done;
234                 }
235
236                 if (file_printf(ms, " %s", type) == -1)
237                         goto done;
238
239                 if (executable)
240                         if (file_printf(ms, " executable") == -1)
241                                 goto done;
242
243                 if (has_long_lines)
244                         if (file_printf(ms, ", with very long lines") == -1)
245                                 goto done;
246
247                 /*
248                  * Only report line terminators if we find one other than LF,
249                  * or if we find none at all.
250                  */
251                 if ((n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) ||
252                     (n_crlf != 0 || n_cr != 0 || n_nel != 0)) {
253                         if (file_printf(ms, ", with") == -1)
254                                 goto done;
255
256                         if (n_crlf == 0 && n_cr == 0 && n_nel == 0 && n_lf == 0) {
257                                 if (file_printf(ms, " no") == -1)
258                                         goto done;
259                         } else {
260                                 if (n_crlf) {
261                                         if (file_printf(ms, " CRLF") == -1)
262                                                 goto done;
263                                         if (n_cr || n_lf || n_nel)
264                                                 if (file_printf(ms, ",") == -1)
265                                                         goto done;
266                                 }
267                                 if (n_cr) {
268                                         if (file_printf(ms, " CR") == -1)
269                                                 goto done;
270                                         if (n_lf || n_nel)
271                                                 if (file_printf(ms, ",") == -1)
272                                                         goto done;
273                                 }
274                                 if (n_lf) {
275                                         if (file_printf(ms, " LF") == -1)
276                                                 goto done;
277                                         if (n_nel)
278                                                 if (file_printf(ms, ",") == -1)
279                                                         goto done;
280                                 }
281                                 if (n_nel)
282                                         if (file_printf(ms, " NEL") == -1)
283                                                 goto done;
284                         }
285
286                         if (file_printf(ms, " line terminators") == -1)
287                                 goto done;
288                 }
289
290                 if (has_escapes)
291                         if (file_printf(ms, ", with escape sequences") == -1)
292                                 goto done;
293                 if (has_backspace)
294                         if (file_printf(ms, ", with overstriking") == -1)
295                                 goto done;
296         }
297         rv = 1;
298 done:
299         free(utf8_buf);
300
301         return rv;
302 }
303
304 /*
305  * Encode Unicode string as UTF-8, returning pointer to character
306  * after end of string, or NULL if an invalid character is found.
307  */
308 private unsigned char *
309 encode_utf8(unsigned char *buf, size_t len, unichar *ubuf, size_t ulen)
310 {
311         size_t i;
312         unsigned char *end = buf + len;
313
314         for (i = 0; i < ulen; i++) {
315                 if (ubuf[i] <= 0x7f) {
316                         if (end - buf < 1)
317                                 return NULL;
318                         *buf++ = (unsigned char)ubuf[i];
319                 } else if (ubuf[i] <= 0x7ff) {
320                         if (end - buf < 2)
321                                 return NULL;
322                         *buf++ = (unsigned char)((ubuf[i] >> 6) + 0xc0);
323                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
324                 } else if (ubuf[i] <= 0xffff) {
325                         if (end - buf < 3)
326                                 return NULL;
327                         *buf++ = (unsigned char)((ubuf[i] >> 12) + 0xe0);
328                         *buf++ = (unsigned char)(((ubuf[i] >> 6) & 0x3f) + 0x80);
329                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
330                 } else if (ubuf[i] <= 0x1fffff) {
331                         if (end - buf < 4)
332                                 return NULL;
333                         *buf++ = (unsigned char)((ubuf[i] >> 18) + 0xf0);
334                         *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
335                         *buf++ = (unsigned char)(((ubuf[i] >>  6) & 0x3f) + 0x80);
336                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
337                 } else if (ubuf[i] <= 0x3ffffff) {
338                         if (end - buf < 5)
339                                 return NULL;
340                         *buf++ = (unsigned char)((ubuf[i] >> 24) + 0xf8);
341                         *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
342                         *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
343                         *buf++ = (unsigned char)(((ubuf[i] >>  6) & 0x3f) + 0x80);
344                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
345                 } else if (ubuf[i] <= 0x7fffffff) {
346                         if (end - buf < 6)
347                                 return NULL;
348                         *buf++ = (unsigned char)((ubuf[i] >> 30) + 0xfc);
349                         *buf++ = (unsigned char)(((ubuf[i] >> 24) & 0x3f) + 0x80);
350                         *buf++ = (unsigned char)(((ubuf[i] >> 18) & 0x3f) + 0x80);
351                         *buf++ = (unsigned char)(((ubuf[i] >> 12) & 0x3f) + 0x80);
352                         *buf++ = (unsigned char)(((ubuf[i] >>  6) & 0x3f) + 0x80);
353                         *buf++ = (unsigned char)((ubuf[i] & 0x3f) + 0x80);
354                 } else /* Invalid character */
355                         return NULL;
356         }
357
358         return buf;
359 }